Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

7.1.1.3 Hoses, cables, and extension rods shall be cleaned free of visible debris with suitable sanitary damp wipes at the point they are withdrawn from exposed ventilation system components or containment areas into general occupant areas.

7.1.2 Upon removing duct diffusers and grilles prior to cleaning, the ventilation system/duct cleaning firm shall provide adequate containment measures to prevent contaminant exposure from accumulated debris on these devices.

7.2 Equipment: All service equipment must operate on standard 110 VAC, 20A circuits.

7.2.1 Vacuum Collection Equipment: All vacuum collection equipment or air filtration devices shall utilize a minimum of HEPA filtration (99.97% at 0.3 micron) final collection efficiency at the device's exhaust. Multi-sectioned equipment must not be opened or detached in occupied areas once contaminated with debris. Vacuum collection equipment shall provide sufficient negative airflow velocity in the ventilation system zone being serviced to draw dislodged debris from the mechanical cleaning device to the vacuum’s collection chamber (typically a minimum of 3000 feet per minute (fpm) in the portion of the HVAC system being cleaned.

7.2.2 Pressurized Air Source Used for Cleaning Devices: Must provide a minimum of 175 PSI at a volume of 15 cubic feet per minute. Device must provide pressurized air free of significant moisture, oil and toxic vapors, or be equipped with adequate filtration and dryers to remove such contamination. The ventilation system/duct cleaning firm shall provide ongoing documentation of the device's delivery of contaminant-ffee pressurized air.

7.3 Component Cleaning: Mechanical Cleaning procedures include the dislodging of WTC-related dust and debris on the interior surfaces of the ventilation system by manual, mechanical, pneumatic, or hydro-agitation. Loosened debris shall be collected and removed from the ventilation system using suitable vacuum collection equipment and/or HEPA vacuuming methods, as specified.

7.3.1 Cleaning Non-Porous ventilation system components: Cleaning methods shall be used that will render the ventilation system components visibly clean. No cleaning method shall be used which will damage components of the ventilation system or significantly alter the integrity of the system.

7.3.2 Cleaning Porous Ventilation System Components: Cleaning method shall be used that will render the ventilation system components visibly clean and minimize fiber release from the porous ventilation system component surface. No cleaning method should be used which will damage components of the ventilation system or significantly alter the integrity of the system. Porous ventilation system components which exhibit increased potential for fiber release (i.e. damaged internal surface bond or coating, and open internal seams and joints) shall be replaced or encapsulated with a product approved for that purpose upon completion of Mechanical Cleaning procedures.

7.4 Encapsulation of Ventilation System Components: Encapsulation of porous or degraded porous ventilation system components shall be employed only after cleaning and successful 6

NYC-WTC_000145210